Protective device for ventilating fans



March 25 1924. 1,487,766

I A. G. SUTCLIFFE PROTECTIVE DEVICE FOR VENTILATING FANS Filed Nov. 13, 1919 4 E x i 25 i I l i T 96 I H .J Lira Brier:

Patented Mar. 25, 1924.

UNITED STATES PATENT OFFICE.

ARTHUR G. SUTCLIFFE, OF CHICAGO, ILLINOIS, ASSIGNOR TO ILG ELECTRIC VEN- TILLTING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF LOUISIANA,

PROTECTIVE DEVICE FOR VENTILATING FANS.

Application filed November 13, 1919. Serial No. 837,732.

To all whom it may concern:

Be it known that I, ARTHUR G. SUT- ourrn, a citizen of the United States, residing in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Protective Devices for Ventilating Fans, of which the followin is a specification.

his invention relates to ventilating fans 1 of that type known as direct driven fans wherein the electric or other motor is applied directly to the shaft of the fan. Such ans are commonly located in openings in walls and operate to draw off the more or less foul or tainted air in the rooms towhich they are applied. Where such fans are driven by electric motors applied directly to the fan shaft, the current of air drawn off by the fan necessarily passes over and in contact with the frame and windings of the motor, and where this air is more or less charged with corrosive fumes and gases such as are found in chemical and other labora tories, paint-shops, kitchens, factories, machine shops, and the like, the latter exert an injurious effect upon the arts of the motor.

In Letters Patent to obert A. Ilg, No. 831,284, dated September 18, 1906, there is disclosed a protective device which also embodies an automatic cooling of the motor, and consists substantially of a hood covering the motor, with a suction pipe leading from a point exterior to the room or chamber containing the motor and tapping said hood,

and said hood having a relatively large central opening adjacent to the suction side of the fan, whereby when the fan is in operation a current of cooling air from outdoors or an adjacent room to that being ventilated is drawn over and thru the motor. This construction both rotects and cools the motor so long as the atter is in operation; but experience has shown that when the fan and motor are idle, the deleterious gases will enter the front opening end of the hood and exert their injurious effects upon the parts of the motor.

The purpose or object of my present invention is to provide an improved construction of motor protective and cooling device for fans of this character which shall be an improvement upon the device of the aforesaid Letters Patent in the way of protecting and cooling the motor at all times; that is,

66 both when it is operating and when it is idle.

To this end my present invention differs from the device of the aforesaid patent in that the motor is fully inclosed, so as to prevent the access of the injurious gases there to, and the cooling and ventilating efiect is obtained by two or more air ducts communicating with the hood of the motor and with a source of external air and is based on the thermo-siphon principle; the heated air in the motor hood or casing flowing upwardly thru the upper pipe, and thereby causing a flow of cool air in the lower pipe into the motor hood or casing.

My present invention, its principle and mode of operation, and the advantages inhering therein will be readily understood and appreciated by those skilled in the art from the following detailed description, taken in connection with the accompanying drawing wherein-' Fi 1 is a central vertical section thru a venti ating fan equipped with my present im rovement; and

ig. 2 is a similar view of a modification wherein the supporting arms 'of the motor frame are made tubular and serve the function of the ventilati pipes.

Referring first to tlle form of invention illustrated in Fig. 1, 5 designates a wall, which may be assumed to be an external wall of a kitchen or a laboratory, having an openin 6 in which is set an annular fan casing As herein shown, the space to the right of the wall 5 may be assumed to represent the interior of the room or chamber to be ventilated, and the s ace to the left of said wall ma be assum to represent the outer atmosp ere or other room or chamber into whichthe fan discharges.

8 designates a ventilating fan of the usual form and type, which is mounted on a fan shaft 9 disposed coaxially with the fan casing 7 and journaled in anti-friction bearings 10 and 11, the bearing 10 being carried by a front hood member 12 secured to the field frame 13 of the motor, and the latter being carried by a rear conical frame piece 14 likewise secured to the field frame 13,the frame piece 14 being formed with upper and lower openings 15 and 16, respectively. The motor is supported from the fan casing 7' by a ring 17 surrounding and secured to the field frame 13 and connected to the fancasing 7 by a plurality of radial arms 18. As the invention is not concerned with the paras vi ticular type of motor, the latter need not herein be further described.

Completely covering the outer end of the motor, or that which is remote from the fan 8 is a hood section 19, the inner open end of which is preferably secured to the motor supportin ring 17 It will thus be seen that the front ood section 12, the field frame 13 and the rear hood section 19 together constitute a hood or casing completely inclosing the motor, and guarding the latter against the inflow of fumes and gases from the room in which the motor is located.

From the top of the rear hood section 19 there extends an upwardly and forwardly curved pipe 20, the upper end of which is fitted into an opening 21 in the upper portion of the fan casing 7 From the lower side of the rear hood section 19 there extends a downwardly and forwardly curved pipe 22, the lower end of which is fitted into an opening 23 in the lower side of the fan casing 7. Communicating with the upper end of the pipe 22 there is preferably employed a short forwardly inclined pipe section 24:, the upper end of which extends thru the opening 16 in the frame piece 14; the purpose of this extension being to direct the upward flowing current of air in the pipe 22 .against the field coils, pole pieces, and armature of the motor.

When the motor is running, considerable heat is generated thereby, which heats up the air within the protective hood or casing surrounding the motor, and this heated air rises and flows upwardly and outwardly thru the pipe 20. This outflow of the heated air sets up a corresponding inflow of cool air thru the pipe 22, on the thermo-siphon principle, so that,as long as the motor is at Work, it is bathed in a current of cool fresh air flowing thru the pipe 22, the motor casing and the pipe 20, whereby the temperature of the motor is maintaind at a safe point, and over-heating is prevented. When the motor is idle and cold, of course this thermo-siphon flow of air is interru ted, but at such times it is not necessary or motor cooling and ventilating purposes, and at such times the hood or casing completely enveloping the motor protects the latter against the injurious effects of corrosive fumes and gases.

Fig. 2 illustrates a somewhat simpler ,embodiment of the same inventive principle. In this construction the separate pipes 20 and 22 for the inflow and outflow of the air are dispensed with, and the motor frame is equipped with upper and lower supporting arms 25 and 26, respectively, that are tubular as shown. The outer ends of the arms 25 and 26 extend thru the wall 5, as shown,

and the inner ends of said arms communicate with holes 27 and 28 formed in the field frame 10, so that the current of air from the lower tubular arm 26 flows directly to and thru the field of the motor, the-heated air rising and flowing outwardly thru the tubular arm 25. The oprative principle is the same as that of the construction shown in Fig 1, substantially the only difference being that in the construction of Fi 2 the members 25 and 26 serve the double gunction of motor supporting arms and air ducts.

So far as the automatic cooling eflect is concerned, the upper end of the pipe 20 or 25 may terminate within the room containing the motor, although in such case the motor is not as fully rotected against the effects of foul'gases, dirt, etc. as in the preferred arrangement shown.

It is believed that the construction, rinciple of operation and mechanical a vanta es of my present improvement will be in ly understood from the foregoing description. Manifestly, the details of structure may be varied, and the number of air ducts increased as desired, without departing from the principle of the invention or sacrificing any of the advantages obtained. Hence, I do not limit the invention to the particular embodiments herein shown and descibed, but reserve all such variations and modifications as fall within the purview of the appended claims.

I claim:

1. The combination with a wall, of an electric motor mounted on one side of said wall, a casing enclosing said motor, an outflow pi e for heated air extendin upwardly from tie top of said casing, an an inflow pipe for cool air extendin downwardly from the bottom of said casing, the upper and lower ends of said outflow and inflow pipes communicating through said wall with the space on the other side of the latter.

2. The combination with a wall, of an electric motor dis sed'on one side of said wall, a casing enc osing said motor, an up wardly extending pi connected to and communicating with t 0 upper side of said casing and at its upper end extending through said wall, and a downwardly extending pi e connected to and communicating with t e lower side of said casing and at its lower end extending throu h said wall, said pipes constituting means or supporting said casing and motor on said wall and also affording a thermo-siphon flow of air through said motor casing from and to points on the opposite side of said wall from said motor.

ARTHUR G. SUTCLIFFE. 

